D. S. Bondar, I. P. Levchuk, V. I. Maslov, and I. N. Onishchenko, “TRANSFORMER RATIO DEPENDENCE ON BUNCH LENGTH AT NON-LINEAR WAKEFIELD EXCITATION IN PLASMA BY ELECTRON BUNCH WITH GAUSSIAN CHARGE DISTRIBUTION”, East Eur. J. Phys., vol. 5, no. 2, pp. 72-77, Jun. 2018.